The present invention relates to lenses with variable focal length in general. More precisely, it relates to liquid crystal lenses wherein the gradient profile of liquid crystal molecules acts as an optical lens for incoming light.
The ability to quickly change the focal length of lenses by means of electronic control may be necessary in systems in which it is difficult to integrate bulky optical systems or mechanics for adjusting such systems mechanically. Liquid crystal lenses with an electronically controlled focal length can allow for rapid electronic variation of the lens focal length without requiring the mechanical manipulation of the optical path.
Existing techniques for controlling the focal length of liquid crystal optical devices rely on non-uniform distributions of the external electric or magnetic field for varying the refractive index of the liquid crystal layer. Such systems often include an electrode in contact with the liquid crystal layer to provide the electric or magnetic field to the optical lens system. In order to create non-uniform distributions of the external field, these systems require specific electrode patterns and a significant number of components. These complex electrode structures and bulky electronic components are difficult to integrate service and maintain. Therefore, it is desired to have a liquid crystal optical device having a simple system structure for highly integrated applications.